Cranks but will not start

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Hey first I wanted to thank everyone who left in my previous post getting me to this point.

II have a Mercruiser 470 that will now crank like a dream but will not turn over. What are the easiest way to test for fuel spark and air. She had gas I just put it in her.
Thanks
 

Gordon88

Cadet
Joined
Jun 19, 2012
Messages
17
Re: Cranks but will not start

Well here are some quick ways ,

Pull a sparkplug out and plug the plugwire back into it ground it to the block and crank the engine over you should see a blue spark jumping in the gap.

For fuel i would just start at the source if it has a mechanical fuel pump pull a fuel line off at before the carb and crank eng over to see if its pumping fuel if its EFI same thing but you can just turn the key over and it should pump fuel,

I also had fuel pump issues before and if your getting spark then try and use some starter fluid spray in carb and fire the engine that way
maybe if you get the fuelpump primed up it will start on its own Note"this only worked for me because my fuel pump was mecanical".
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

Any way to tell if it's electronic or mechanical? The boat is 89regal if that would help at all
 
Joined
May 17, 2013
Messages
9
Re: Cranks but will not start

Well, the easiest way to tell if its electronic or points is to take off the distributor cap and take a look at what is underneath it if it has a condenser then its points if not then it is electric. If it is points then you might also want to consider converting it to electric. message me if you want a guide that will further explain this.
 
Joined
Mar 27, 2010
Messages
3,008
Re: Cranks but will not start

The Regal part doesn't mean squat... They only made the 470 with a mechanical pump but who knows what's been done to it over the years.

A mechanical pump is it attached to the engine and has a somewhat clear/yellowish plastic/line running up to the carb and a metal line also going to the carb.... or does it have wires going to it.

A mechanical pump is driven by the engine, an electrical pump is driven by an electric motor with wires powering it up....
 

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: Cranks but will not start

Almost certantly mechanical but.... Follow the fuel line down from the carb. The fuel pump should be bolted to the side of the block. if it is it's mechanical
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Cranks but will not start

II have a Mercruiser 470 that will now crank like a dream but will not turn over.

Crank and turn over means the same thing, the starter spinning the engine.
What your engine isn't doing is starting and running.

Do you have spark?

Do not use starting fluid. If you have spark (good bright blue spark) then squirt some gas into the carb and see if it fires.
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

Okay, thanks for the replies. Im gonna try to work on it tomorrow as today in Maryland it's storming with tornado warnings. So i think ill say inland for the day
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

Sorry to go off topic for a quick second but while the weather is bad up here, i figured i'd look for other parts the boat will need. I found an outdrive with an 1.84 ratio is that compatible with my 470?

Also my deck has permanent carpet in place, but i want to replace with something that sheds water so as to perserve my deck under it. Thoughts on KIWIGRIP
 

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: Cranks but will not start

I found an outdrive with an 1.84 ratio is that compatible with my 470?

Yes. The guys on the restoration part of this site can probably help you out with the flooring questions.
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

Thank you, he was wanting 250 im gonna try and talk him down to 100 for it. He said it was in working condition when it was removed, anything special i should look for on an outdrive already removed?

I should be getting back on schedule this weekend after my rugby tournament, ill let you guys know what i find out.

Thank you all again for the advice.
 

Gordon88

Cadet
Joined
Jun 19, 2012
Messages
17
Re: Cranks but will not start

i was short and didnt explain very well on how to go about finding if your geting fuel or not when you get around to it let this forum know any updates on your issues i found that there are very helpful ppl on this forum!
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

Okay just got down here. Looks to still be mechanical fuel pump attached to the block starboard side. Which line should I pull to test? The hard line or the clear plastic one? Once that's done I'll move to spark and lastly a compression test
 

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: Cranks but will not start

The hard line, the clear one is a relief line in case of a rupture of the fuel pump diaphragm. Should be dry, if there is gas in it then you probably have a ruptured diaphragm.
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

Okay I didn't have a large enough wrench handy so I detached the metal line at the fuel pump is that okay? I cranked her over and nothing came out the nozzle isn't even wet. Is there a way to check for clogged fuel filter without buying a replacement first? The fuel filter is prior to the pump
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

Also Want to check spark starting back at the coil. Cool should be 12 volts while cranking right
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Cranks but will not start

Also Want to check spark starting back at the coil. Cool should be 12 volts while cranking right

You should see battery voltage at the + terminal, but it won't be 12V. Crank the engine with your volt meter hooked to the battery first to see what you should get.
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

Okay so coil should match battery while cranking. Understood I'll give it a shot
 

dowtom

Seaman
Joined
May 23, 2012
Messages
72
Re: Cranks but will not start

So I measured the battery at cranking is 10.4 the coil is 11.4 when not cranking and 9.6 while cranking. Is that acceptable?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Cranks but will not start

Get a jumper wire, hook it from battery + to the coil + terminal and see if it starts or gets good spark.
 
Top